authoritative: use other than for zone xfer?

[Kevin Darcy]

Len Conrad wrote:

> Other than enabling/disabling zone transfers, what other
> advantage/disadvantage is there to an NS being authoritative or not?
>
> eg, who/what else cares if an authoritative NS is answering with correct
> data but non-authoritatively?

Off the top of my head, if a nameserver answers with RCODE=NOERROR and
ANCOUNT=0, then I believe the querier needs to look at the AA bit to
distinguish between a referral and "no data of requested type found" from
an authoritative nameserver. If it's an authoritative answer, the query is
finished, but if the querier thinks it's an attempted referral, it'll mark
the server as lame and keep on looking elsewhere for the data.  So there's
at least one case where the AA bit is necessary even for the basic
query-resolution function of DNS.

I can't help wondering why you ask this question. Is it just idle
curiosity, or are you trying to get away with doing something illegal in a
master zone? Most of those restrictions are there for a good reason.


- Kevin